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Biomedical subjects

L W Stevenson

Publications and source records attributed to L W Stevenson.

At least 37 records · Page 2Linked to original sources
PubMed2000

The prognostic implications of renal insufficiency in asymptomatic and symptomatic patients with left ventricular systolic dysfunction.

OBJECTIVES: The present analysis examines the prognostic implications of moderate renal insufficiency in patients with asymptomatic and symptomatic left ventricular systolic dysfunction. BACKGROUND: Chronic elevations in intracardiac filling pressures may lead to progressive ventricular dilation and heart failure progression. The ability to maintain fluid balance and prevent increased intracardiac filling pressures is critically dependent on the adequacy of renal function. METHODS: This is a retrospective analysis of the Studies of Left Ventricular Dysfunction (SOLVD) Trials, in which moderate renal insufficiency is defined as a baseline creatinine clearance <60 ml/min, as estimated from the Cockroft-Gault equation. RESULTS: In the SOLVD Prevention Trial, multivariate analyses demonstrated moderate renal insufficiency to be associated with an increased risk for all-cause mortality (Relative Risk [RR] 1.41; p = 0.001), largely explained by an increased risk for pump-failure death (RR 1.68; p = 0.007) and the combined end point death or hospitalization for heart failure (RR 1.33; p = 0.001). Likewise, in the Treatment Trial, multivariate analyses demonstrated moderate renal insufficiency to be associated with an increased risk for all-cause mortality (RR 1.41; p = 0.001), also largely explained by an increased risk for pump-failure death (RR 1.49; p = 0.007) and the combined end point death or hospitalization for heart failure (RR 1.45; p = 0.001). CONCLUSIONS: Even moderate degrees of renal insufficiency are independently associated with an increased risk for all-cause mortality in patients with heart failure, largely explained by an increased risk of heart failure progression. These data suggest that, rather than simply being a marker of the severity of underlying disease, the adequacy of renal function may be a primary determinant of compensation in patients with heart failure, and therapy capable of improving renal function may delay disease progression.

Aged↗
PubMed2000

Randomized trial of candesartan cilexetil in the treatment of patients with congestive heart failure and a history of intolerance to angiotensin-converting enzyme inhibitors.

BACKGROUND: Many patients with congestive heart failure do not receive the benefits of angiotensin-converting enzyme (ACE) inhibitors because of intolerance. We sought to determine the tolerability of an angiotensin II receptor blocker, candesartan cilexetil, among patients considered intolerant of ACE inhibitors. METHODS: Patients with CHF, left ventricular ejection fraction less than 35%, and history of discontinuing an ACE inhibitor because of intolerance underwent double-blind randomization in a 2:1 ratio to receive candesartan (n = 179) or a placebo (n = 91). The initial dosage of candesartan was 4 mg/d; the dosage was increased to 16 mg/d if the drug was tolerated. A history of intolerance of ACE inhibitor was attributed to cough (67% of patients), hypotension (15%), or renal dysfunction (11%). RESULTS: The study drug was continued for 12 weeks by 82.7% of patients who received candesartan versus 86.8% of patients who received the placebo. This 4.1% greater discontinuation rate with active therapy was not significant; the 95% confidence interval ranged from 4.8% more discontinuation with placebo to 13% more with candesartan. Titration to the 16-mg target dose was possible for 69% of patients who received candesartan versus 84% of those who received the placebo. Frequencies of death and morbidity were not significantly different between the candesartan and placebo groups (death 3.4% and 3.3%, worsening heart failure 8.4% and 13.2%, myocardial infarction 2.8% and 5.5%, all-cause hospitalization 12.8% and 18.7%, and death or hospitalization for heart failure 11.7% and 14.3%). CONCLUSIONS: Candesartan was well tolerated by this population. The effect of candesartan on major clinical end points, including death, remains to be determined.

Aged↗
PubMed2000

Drug therapy of heart failure caused by systolic dysfunction in the elderly.

The presence of multiple medical illnesses often distinguishes elderly patients with heart failure and can make pharmacologic management of symptomatic heart failure challenging in this population. Physiologic changes that occur with normal aging may complicate clinical assessment. Limited data from large clinical trials of heart failure therapy are applicable to aged patients. Available data suggest that elderly patients should be treated with the same regimen as younger patients but that more careful attention should be paid to dosing, especially when initiating a new drug. History and physical examination techniques can be used to uncover evidence of congestion and inadequate perfusion and are critical adjuncts when making therapeutic decisions. The objectives of therapy for elderly patients with heart failure must be individualized within the larger context of patients' goals and stage of life.

Adrenergic Antagonists↗
PubMed2000

Early outcome of initiating amiodarone for atrial fibrillation in advanced heart failure.

BACKGROUND: Little information exists about the early outcomes of initiating amiodarone for atrial fibrillation in patients with advanced heart failure. This study assessed the initial rate of success and complications of amiodarone therapy initiated for patients with atrial fibrillation during hospitalization for heart failure. METHODS: We reviewed medical records for 37 consecutive patients with left ventricular ejection fractions </=40% who underwent initiation of amiodarone for atrial fibrillation during hospitalization on a heart failure service. RESULTS: Atrial fibrillation was present in 35 (95%) and atrial flutter in 2 (5%), with mean duration of 30 months. New York Heart Association class was 3.1 (+/-1.1). Left ventricular ejection fraction was 24% +/- 7%. All patients had received oral amiodarone with an initial dose of 1.2 +/- 0.2 g/day. Bradyarrhythmia led to discontinuation of digoxin in 12 (32%) patients and to permanent pacemaker placement in 7 (19%) patients. Conversion to sinus rhythm occurred spontaneously in 2 patients and after electrical cardioversion in 26 patients, for an initial success of 76%. After a median follow-up of 9.5 months, 21 of 37 (57%) patients remained in sinus or atrial-paced rhythm. Amiodarone complications occurred after discharge in 5 (14%) patients, 4 with hypothyroidism. CONCLUSIONS: Amiodarone with electrical cardioversion has a high initial success rate for treatment of atrial fibrillation in patients with heart failure with advanced systolic dysfunction. The major early side effect was bradyarrhythmia, frequently requiring discontinuation of digoxin or permanent pacemaker placement.

Administration, Oral↗
PubMed2000

Freedom from congestion predicts good survival despite previous class IV symptoms of heart failure.

BACKGROUND: This study determined whether evidence of congestion after 4 to 6 weeks of heart failure management predicted outcome for patients hospitalized with chronic New York Heart Association class IV symptoms. Class IV symptoms predict high mortality rates, but outcome is not known for patients who improve to establish freedom from congestion. Revised estimates at 1 month could facilitate decisions regarding transplantation and other high-risk interventions. METHODS: At 4 to 6 weeks after hospital discharge, 146 patients were evaluated for congestion by 5 criteria (orthopnea, jugular venous distention, edema, weight gain, and new increase in baseline diuretics). Heart failure management included inpatient therapy tailored to relieve congestion, followed by adjustments to maintain fluid balance during the next 4 weeks. RESULTS: Freedom from congestion was demonstrated at 4 to 6 weeks in 80 (54%) patients, who had 87% subsequent 2-year survival compared with 67% in 40 patients with 1 or 2 criteria of congestion and 41% in 26 patients with 3 to 5 criteria. The Cox proportional hazards model identified left ventricular dimension, pulmonary wedge pressure on therapy, and freedom from congestion as independent predictors of survival. Persistence of orthopnea itself predicted 38% 2-year survival (without urgent transplantation) versus 77% in 113 without orthopnea. Serum sodium was lower and blood urea nitrogen and heart rate higher when orthopnea persisted. CONCLUSIONS: The ability to maintain freedom from congestion identifies a population with good survival despite previous class IV symptoms. At 4 to 6 weeks, patients with persistent congestion may be considered for high-risk intervention.

Disease Progression↗
PubMed1999

Aggravated renal dysfunction during intensive therapy for advanced chronic heart failure.

BACKGROUND: Chronic heart failure is associated with impaired renal function, which may worsen during therapy. The incidence, predictors, and consequences of aggravated renal dysfunction (ARD) in patients undergoing intensive therapy for advanced chronic heart failure are unknown. METHODS: We reviewed the experience of 48 consecutive patients hospitalized for treatment of advanced chronic heart failure who underwent intravenous diuretic therapy with a weight loss of >/=2 kg. Evaluation included baseline renal function and echocardiography in all patients and hemodynamic measurements in 38 (79%) patients. RESULTS: ARD, defined as >/=25% increase in serum creatinine concentration to >/=2 mg/dL, developed in 10 (21%) patients. Patients with ARD developing were older (aged 58 +/- 16 years vs 51 +/- 13 years; P =.006) and had lower baseline creatinine clearance (49 +/- 21 mL/min vs 74 +/- 26 mL/min; P =.01) but had the same serum creatinine at baseline. They were more likely to have atrial fibrillation (70% vs 29%, P =.02) but did not have lower filling pressures, cardiac output, or estimated renal perfusion pressure. Length of stay was longer if ARD developed (median 17 vs 9 days, P =.02). Mortality rate after discharge was increased in the patients with ARD (relative risk 5.3, P =.002). CONCLUSIONS: In patients undergoing intensive treatment for heart failure, ARD is common and clinically significant. The relation among baseline factors, ARD, and worsened outcome may reflect complex cardiorenal interactions. Better understanding of the causes and prevention of ARD during heart failure therapy may in the future lead to better outcomes.

Adult↗
PubMed1999

The 6-min walk and peak oxygen consumption in advanced heart failure: aerobic capacity and survival.

BACKGROUND: This study sought to determine to what extent the 6-min walk (6MW) distance in advanced heart failure predicts aerobic capacity and provides comparable information regarding survival. Peak oxygen uptake ( VO(2)) and the 6MW both describe function and predict outcome over a wide range of heart failure, but their determinants and implications may differ within a narrower clinical spectrum. This study compared 6MW with aerobic capacity both at peak exercise and during low-level cycling. METHODS AND RESULTS: Both the 6MW and symptom-limited cycle ergometry were performed by 307 patients of whom 264 patients additionally performed 6 min of 20-W cycling to estimate aerobic capacity during sustained low-level activity. In the first 198 patients, multivariate analysis of survival was performed with the 6MW and peak VO (2). Patients achieved the 6MW of 393 +/- 104 m and peak VO (2) of 14 +/- 5 mL/kg per minute. Although low peak VO (2) was more likely with the shorter 6MW, the relation was weak within peak VO (2) range of 10 to 20 mL/kg per minute (n = 213, 69% of patients, r = 0.28). During 20-W exercise, VO (2) was 9.2 +/- 2.0 mL/kg per minute, with respiratory exchange ratio poorly correlated with the 6MW. In contrast to peak VO (2), the 6MW in meters did not predict survival. Division into short, medium, and long walks, however, supplemented simple clinical description. CONCLUSIONS: Although helpful in broader populations for identification of patients with obvious clinical compromise, the 6MW distance is not a surrogate for peak VO (2) in assessing aerobic capacity or prognosis for individuals with advanced heart failure.

Exercise Test↗
PubMed1999

The REMATCH trial: rationale, design, and end points. Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure.

BACKGROUND: Because left ventricular assist devices have recently been approved by the Food and Drug Administration to support the circulation of patients with end-stage heart failure awaiting cardiac transplantation, these devices are increasingly being considered as a potential alternative to biologic cardiac replacement. The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) trial is a multicenter study supported by the National Heart, Lung, and Blood Institute to compare long-term implantation of left ventricular assist devices with optimal medical management for patients with end-stage heart failure who require, but do not qualify to receive cardiac transplantation. METHODS: We discuss the rationale for conducting REMATCH, the obstacles to designing this and other randomized surgical trials, the lessons learned in conducting the multicenter pilot study, and the features of the REMATCH study design (objectives, target population, treatments, end points, analysis, and trial organization). CONCLUSIONS: We consider what will be learned from REMATCH, expectations for expanding the use of left ventricular assist devices, and future directions for assessing clinical procedures.

Heart Failure↗
PubMed1999

Effect of intensive therapy for heart failure on the vasodilator response to exercise.

OBJECTIVES: The purpose of the study was to evaluate the lower extremity vascular responsiveness to metabolic stimuli in patients with heart failure and to determine whether these responses improve acutely after intensive medical therapy. BACKGROUND: Metabolic regulation of vascular tone is an important determinant of blood flow, and may be abnormal in heart failure. METHODS: The leg blood flow responses were measured in 11 patients with nonedematous class III-IV heart failure before and after inpatient medical therapy and in 10 normal subjects. Venous occlusion plethysmography was used to measure peak blood flow and total hyperemia in the calf after arterial occlusion and also after isotonic ankle exercise. Measurements were repeated following short-term inpatient treatment with vasodilators and diuretics administered to decrease right atrial pressure (18+/-2 to 7+/-1 mm Hg), pulmonary wedge pressure (32+/-3 to 15+/-2 mm Hg), and systemic vascular resistance (1581+/-200 to 938+/-63 dynes.s.cm(-5), all p < 0.02). RESULTS: Leg blood flow at rest, after exercise, and during reactive hyperemia was less in heart failure patients than in control subjects. Resting leg blood flow did not increase significantly after medical therapy, but peak flow after the high level of exercise increased by 59% (p = 0.009). Total hyperemic volume in the recovery period increased by 73% (p = 0.03). Similarly, the peak leg blood flow response to ischemia increased by 88% (p = 0.04), whereas hyperemic volume rose by 98% (p = 0.1). CONCLUSIONS: The calf blood flow responses to metabolic stimuli are blunted in patients with severe heart failure, and improve rapidly with intensive medical therapy.

Blood Flow Velocity↗
PubMed1999

Relationship between right and left-sided filling pressures in 1000 patients with advanced heart failure.

BACKGROUND: Elevated left ventricular filling pressures present a major target of therapy for symptomatic heart failure but are difficult to assess directly. Because the relationship of left- and right-sided pressures remains ill defined in chronic heart failure, this study compared 3 right-sided measurements (right atrial [RA] pressure, pulmonary artery systolic [PAS] pressure, and severity of tricuspid regurgitation [TR]) to the pulmonary capillary wedge (PCW) pressure. METHODS: Hemodynamic measurements and echocardiography were available from 1000 patients undergoing transplant evaluation. Right atrial and PAS pressure, and TR severity were compared to PCW pressure. For 754 patients undergoing repeat measurements, changes in RA and PAS pressures were compared to PCW changes. RESULTS: Right atrial pressure correlated with PCW pressure (r = 0.64), regardless of etiology or TR severity. Right atrial pressure changes correlated with PCW changes (r = 0.62). Discordance was defined as either RA > or = 10 mm Hg despite PCW < 22 mm Hg (6%) or RA < 10 mm Hg despite PCW > or = 22 mm Hg (15%). For detection of PCW > or = 22 mm Hg, positive predictive values were 88% for RA > or = 10 mm Hg, 95% for PAS > or = 60 mm Hg, and 79% for > or = moderate TR. Pulmonary artery systolic pressure correlated very closely with PCW (r = 0.79), and could be estimated as 2 x PCW. Reduction in PAS pressure during therapy was strongly determined by PCW pressure reduction (r = 0.67). CONCLUSIONS: Accurate estimation of RA pressure can potentially guide therapy of left ventricular filling pressures in approximately 80% of chronic heart failure patients without obvious non-cardiac disease. In this population, elevated PAS pressures are largely determined by elevated left-sided filling pressures.

Diuretics↗
PubMed1998

Recipient-to-donor atrioatrial conduction after orthotopic heart transplantation: surface electrocardiographic features and estimated prevalence.

Recipient-to-donor atrioatrial conduction across a suture line has been rarely reported after orthotopic heart transplantation. The relation of such conduction to symptomatic arrhythmias and its prevalence are not known. Recipient-to-donor atrioatrial conduction was demonstrated in a 28-year-old woman with paroxysmal supraventricular tachycardia 7 years after orthotopic heart transplantation. Atrial tachycardia in the recipient atria conducted 2:1 to the donor atria and was eliminated by radiofrequency catheter ablation of a left-sided atrioatrial electrical connection. The electrocardiogram at rest and during exercise, recorded before ablation of the recipient-to-donor connection, showed frequent atrial premature complexes, with variable coupling to the preceding sinus beats, and a change in P-wave morphology during exercise, which reverted to normal during the recovery period. These findings were eliminated by ablation of the recipient-to-donor connection. To determine the prevalence of recipient-to-donor atrioatrial conduction late after transplantation, we evaluated the exercise electrocardiograms of 50 subjects > 5 years after heart transplantation for these features of recipient-to-donor conduction. At least 1 feature was present in 5 subjects, and both were present in 1 subject. Electrical conduction can occur across surgical suture lines in the atria. Recipient-to-donor atrioatrial conduction may occur in < or = 10% of patients late after heart transplantation. It is a potential cause of arrhythmias that can be effectively treated with radiofrequency catheter ablation.

Adult↗
PubMed1998

Safety and hemodynamic effects of intravenous triiodothyronine in advanced congestive heart failure.

Most patients with advanced congestive heart failure have altered thyroid hormone metabolism. A low triiodothyronine level is associated with impaired hemodynamics and is an independent predictor of poor survival. This study sought to evaluate safety and hemodynamic effects of short-term intravenous administration of triiodothyronine in patients with advanced heart failure. An intravenous bolus dose of triiodothyronine, with or without a 6- to 12-hour infusion (cumulative dose 0. 1 5 to 2.7 microg/kg), was administered to 23 patients with advanced heart failure (mean left ventricular ejection fraction 0.22 +/- 0.01). Cardiac rhythm and hemodynamic status were monitored for 12 hours, and basal metabolic rate by indirect calorimetry, echocardiographic parameters of systolic function and valvular regurgitation, thyroid hormone, and catecholamine levels were measured at baseline and at 4 to 6 hours. Triiodothyronine was well tolerated without episodes of ischemia or clinical arrhythmia. There was no significant change in heart rate or metabolic rate and there was minimal increase in core temperature. Cardiac output increased with a reduction in systemic vascular resistance in patients receiving the largest dose, consistent with a peripheral vasodilatory effect. Acute intravenous administration of triiodothyronine is well tolerated in patients with advanced heart failure, establishing the basis for further investigation into the safety and potential hemodynamic benefits of longer infusions, combined infusion with inotropic agents, oral triiodothyronine replacement therapy, and new triiodothyronine analogs.

Female↗